Water has been commercially cleaned by magnetic seeding and separation technologies for many years. Briefly, these technologies involve adding a magnetic seed material (preferably magnetite) to water that contains fine pollutant particles. Agitating the magnetic seed material and fine pollutant particles in the presence of an organic flocculating agent produces a composite particle that is magnetic and easily removed from the water with either permanent magnets or electromagnets.
A known commercial application of magnetic seeding is the “Sirofloc” technology used in Australia to clean drinking water. This process uses the absorption capacity of magnetite to remove color and other pollutants from water. The spent magnetic seed material (magnetite) settles out by gravity in a clarifier and is then pumped to a magnetite regeneration step that cleans the magnetite so it can be reused.
Another known commercial application of magnetic seeding is the “Comag” process described in Wechsler U.S. Pat. No. 6,099,738. This process employs a high gradient field magnetic collector that uses powerful electromagnets. Once the collector becomes loaded with solids, it is backwashed with air and water to flush the magnetic seed material to a cleaning process. The cleaned magnetic seed material is then reused in the treatment process. The electromagnets in the Comag system have to be de-energized for cleaning. The cleaning process interrupts the flow of water for treatment and high solids loading limits the ability to backwash the system.
There are also various patents covering the use of ballast materials to enhance the clarification of water. These patents disclose the use of micro-sand, garnet, magnetite, and other granular materials with a density greater than water as suitable ballast material used to clarify water. In the ballast clarification process, polymers are used to attach fine pollutant particles to high density ballast materials to increase the settling rate of the pollutant particles. In the “Actiflo” process offered by Kruger Inc. of Cary, N.C., and exemplified by FIG. 1 hereof, the settled particles are pumped to a hydrocyclone for cleaning. The pumping action is intended to break the bond between the ballast and the pollutant particles; then the hydrocyclone centrifugally separates the ballast so it can be returned to the process for reuse. The pollutant particles are then sent to a dewatering system to further reduce their volume.